Improvement of the sensitivity and spatial resolution of pixelated CsI:Tl scintillator with reflective coating

Pixelated-scintillator films used for X-ray image sensors were developed and tested. The air gap between scintillator pixels reduces the transport of visible light photons generated by X-rays into the neighboring pixels so it will maximize the overall spatial resolution as well as the light collection efficiency of an X-ray imager. For further improvement, the inter-pixel gaps and surface are filled and coated with a reflective or a lower refractive material than an CsI(Tl) scintillator. The scintillator films of 30-40 μm thickness were made with thallium-doped CsI by the conventional physical vapour deposition process on glass substrates with a photo resist layer patterned by UV lithography. In this work, the effects on light collection efficiency and spatial resolution of the pixelated-scintillator films before and after reflective coating were evaluated using a CCD sensor and X-rays within the medical diagnostic energy range.